This invention relates to a circular saw having a viewing window on the upper guard.
One of the problems associated with the use of a hand-held circular saw is properly aligning the saw so that the desired cut is achieved. Typically, a user will draw a line on the material to be cut. This line represents the location of the desired cut. The problem arises when the user of the hand-held circular saw attempts to align the blade with the line on the material. The problem continues as the user attempts to keep the blade tracking on the desired cut line.
To assist in the alignment, circular saws are typically provided with a guide slot. The guide slot is usually located on the planar cutting base of the saw, and is positioned in front of, and in line with, the circular saw blade. The user then positions the saw so that the line on the material appears in the guide slot. While the provision of such a guide slot does aid the user in proper saw alignment, problems still exist. First, because the guide slot is located in front of the blade, if the saw blade is not perpendicular relative to the workpiece, the guide slot can be positioned on the cut line while the blade is not. If the user begins to cut the material with the saw in this orientation, it is often difficult to correct the alignment problem. Second, because the blade is covered by a saw guard, the user cannot see the blade as it exits the material, and therefore cannot directly monitor the travel of the blade.
Attempts have been made to allow the user of the saw to view the blade as it exits the material, thereby allowing the user to properly guide the blade along the desired cut line. A device that allows a user to view the blade is disclosed in U.S. Pat. No. 4,450,627. This patent discloses a circular saw with a viewing window on the upper saw guard. The window is intended to allow users of the saw to properly align the saw to the workpiece by allowing them to view the blade. While this viewing window solves the above problems to some degree, its positioning remains a problem.
If the viewing window is not properly positioned, the user will be unable to see the blade exiting the material due to the reflection of light by the transparent section of the viewing window. To compensate, the user may attempt to reposition the light source, such as a flashlight, or may reposition himself relative to the saw. This repositioning can affect efficiency as well as the quality of the work being performed. If the user repositions himself relative to the saw, the resulting position may be an uncomfortable one from which to operate the saw. Further, the trial and error necessary to find the proper position of saw, user and light source wastes the user's time.
The position of the viewing window must also account for the sawdust generated as the saw cuts through the workpiece. If the window is positioned to far forwardly, the sawdust can accumulate on the transparent section of the window and impair the user's view of the blade as it exits the workpiece. The viewing window must therefore be positioned so as to minimize or eliminate the accumulation of sawdust on the viewing window.
Further, circular saws having a viewing window have heretofore not adequately addressed the problem caused by the lower saw guard in relation to the provision of a viewing window. The lower saw guard surrounds the lower portion of the blade when the saw is not in use. When the saw is being used, the front portion of the lower saw guard engages the workpiece and is rotated upwardly to expose the lower portion of the blade. When the lower guard is rotated fully upwardly, the rear portion of the lower saw guard can impair the user's view of the blade through the transparent section of the viewing window. This impairment does not affect the user's view as the cut is initiated, but rather impairs the view when the saw is sufficiently engaged with the workpiece so as to rotate the lower guard to a fully retracted position.
Therefore, a window assembly is needed that is properly positioned in the upper saw guard of a circular saw so that the user can view, from a normal operating position, the blade exiting the workpiece. A window assembly is needed that minimizes any light reflected into the eyes of the user from both above and in front of the viewing window. Further, a window assembly is needed that is properly positioned in the upper saw guard of a circular saw so that the accumulation of sawdust on the viewing window is reduced or eliminated. Finally, a lower saw guard is needed which will allow a user to view the saw blade exiting the workpiece, through a transparent member of the window assembly in the upper saw guard, even when the lower guard is in a fully retracted position.